This disclosure generally relates to the elevator system, and more particularly, to a centrifugally actuated governor that reacts to a speed of the elevator car or counterweight.
A common challenge in elevator design is engineering safety systems to prevent or react to elevator malfunction. One such safety system is the speed governor. Elevator speed governors are designed to prevent elevator cars or counterweights from exceeding a set speed limit. The governor is a component in an automated safety system, which is actuated when the elevator car or counterweight exceeds a set speed and either signals a control system to stop the car or directly engages a safety linkage connected to the safeties to stop the car. One commonly known governor is a centrifugally actuated governor.
A common design of centrifugal governors used in elevator systems employs two masses, sometimes referred to as flyweights, connected kinematically in an opposing configuration by links and pinned to a tripping sheave rotating about a common axis. These interconnected parts create a governor mechanism, which rotates at an angular velocity common with the angular velocity of the sheave. The angular velocity of the rotating masses results in a centrifugal force acting to propel the masses away from the sheave axis of rotation. The movement of the masses is essentially a cantilevering motion radially outward about their pinned attachments to the sheave. A coupler prevents the radial outward movement of the masses up to a set elevator car speed. The coupler commonly includes a spring connected between the sheave and one of the masses, which resists the centrifugal force generated by the angular velocity of the rotating sheave up to a set speed. When the elevator car meets or exceeds a set speed limit, sometimes referred to as an overspeed condition, the governor is actuated. In the overspeed condition, the force of the governor coupler, for example the spring coupler, is overcome by the centrifugal force acting on the masses. The two masses move radially outward and commonly engage a sensor at a first speed, which in turn signals control logic in the elevator system to interrupt power to the elevator machine and release a brake to stop the elevator car. If this is ineffective, at a second higher set speed, movement of the masses enables a safety linkage to engage the safeties and stop the elevator car and/or counterweight.
Some existing elevator systems include a governor assembly having a separate swing jaw and tripping lever. However, these types of governor assemblies require that the tripping lever be manually reset by a mechanic in the field before the elevator system can be used after an overspeed condition requiring activation of the safety linkage to engage the safeties. In other existing elevator systems, the radial movement of the flyweights results in a swing jaw having an integrated tripping lever to approach and ultimately engage a tooth of an adjacent ratchet disc. However, the slow radial movement of the flyweights results in a slow rotation of the swing jaw towards the ratchet disc. As a result of this slow movement, the swing jaw may contact and deflect from an end of a tooth on the ratchet disc, thereby allowing the overspeed condition to continue until proper engagement between the swing jaw and the ratchet is achieved.